The Hollow Children are

Urugal's Son, Child of Filth - deceased (roaches)

Shezeri's Son, Child of Ice - deceased (frogs)

Sefeneil's Son, Child of Famine - deceased (locusts)

Elden's Son, Child of Undeath (moths)

Diamond's Son, Child of Chaos (bats)

Traa's Son, Child of Destruction (hornets)

Genfyllid's Son, Child of Envy (snakes)

Remmhish's Son, Child of Stillbirth (piranhas)

Mstislav's Son, Child of Hatred (scorpions)

Jackson, Child of Pestilence (scarabs)

Guinevere's Son, Child of Darkness (spiders)

Lyzinda's Son, Child of Despair - deceased (centipedes)

Nicolle's Son, Child of Void (ants)

Their unofficial leader is Hollow John, a living skin who served as Jack's Hand.